Technical Field
Embodiments of the subject matter disclosed herein relate generally to apparatuses, methods and systems and, more particularly, to devices, processes, mechanisms and techniques for the characterization of refractory lining of metallurgical vessels by autonomous scanners.
Description of Related Art
Measurement of the interior profile of vessels used in the production of molten metal using high-speed scanning laser range finders is widely used in the metal producing industry. Iron and steel ladles, Basic Oxygen Furnaces (BOFs), Argon-Oxygen Decarburization Vessels (AODs), Electric Arc Furnaces (EAFs), aluminum and copper smelting vessels, foundry furnaces, torpedo cars and bottom blown furnaces (Q-BOP's) are all analyzed using laser scanners to determine the interior refractory profile and calculate remaining lining thickness. In many operations, scanner operators are exposed to harsh environment in order to perform these desired measurements. In other areas of technology, such as military operations, autonomous mobile robots have been used to perform dangerous task, such as ordinance or explosives handling or disposal, field reconnaissance, terrain mapping, and various other procedures. Nevertheless, up to now, autonomous scanners have not been used in the metallurgical industry.
On a worldwide basis, few if any steel producing facilities operate their BOFs and AODs without laser scanner technology to determine the inner refractory profile. In Asia and the Americas, where vessel lifetimes can be upwards of 50,000 heats, laser scans are carried out up to 7 or 8 times in a 24-hour period. In Europe, refractory repair is less common and the furnace is operated to its minimum allowable refractory thickness and then replaced. Typical lining lifetimes are on the order of 3000 heats, and the laser scanner is not used until late in the lifetime of the lining. When the scanner is employed, the measurement data are used primarily to assess the maximum permissible lifetime while maintaining a low probability of breakthrough. In all cases, profile information is used to determine both the remaining lining thickness and the proper set point for the oxygen lance height; the latter determined by volume integration over the measured interior refractory profile. Two primary scanner configurations are currently in use—a mobile scanner and a fixed-position scanner.
A fixed-position scanner is normally mounted in a specific location in the steel mill so as to effect the necessary field of view into the vessel. With the exception of ladle and torpedo car measurement, the fixed-position system is dedicated to the vessel to be measured. Though there remains a cost consequence for this configuration, the system is readily available for measurement using a computer control station typically mounted in the plant control room.
Mobile scanners are typically applied to stationary vessels such as BOFs and AODs. They offer the cost advantage of multiplexing a single system to multiple vessels. BOF, Q-BOP and AOD furnaces are also plagued by skull accumulation in the furnace mouth that limits the field of view into the furnace. By measuring the furnace at various combinations of furnace tilt and mobile system position in front of the furnace, acceptable field of view into the furnace can be maintained and the majority of the interior profile measured.
Measurements are made with a mobile system by the operator first positioning the unit at the approximate first measurement position in front of the furnace—normally the furnace centerline. To avoid excessive thermal shock and spelling of the refractory, the furnaces are typically measured at or near operating temperatures, which can be as high as 1700° C. Under these conditions, heat shields are needed to protect the operator from the intense heat load that results when standing 2 to 3 meters from the vessel's mouth.
With the mobile laser system placed in position by the system's operator, the vessel is tilted to the proper angle to create the required view of the upper section of furnace interior and a scan of the vessel is made from this position. Once the scan is completed, the vessel is tilted to a second orientation to expose the lower section of the furnace interior. A scan is again made and combined with the prior scan. Next, the furnace is tilted to the horizontal position, and the mobile system is moved by the operator to the right of the furnace centerline, in preparation for measuring the left inner section of the furnace. Finally, the mobile system is moved to the left of the furnace centerline, and a fourth scan completed to document the right inner section of the furnace. All scans are then combined to create a data set that comprises the entire (or nearly the entirety) of the furnace interior. As noted, conventional mobile scanners require significant operator physical interventions before, during, and after measurements, thus exposing them to harsh and dangerous environments unnecessarily.
The mobile system offers cost advantages, as well as the flexibility of position that is often needed in the presence of significant furnace mount skull. However, the mobile configuration suffers in both measurement speed and operator safety; the latter being of primary importance in most steel mills. The heat load experienced while measuring a hot vessel is high; human tolerance of the environment this close to the furnace is on the order of seconds. Moreover, debris that collects in the hood region above the furnace can break away and fall into the measurement area. As some of this falling detritus can weigh several pounds or more, there is a real potential for significant bodily injury.
Therefore, based at least on the above-noted challenges and in order to improve safety, reliability and operability of a mobile scanning system, it would be desirable to have apparatuses, processes, and systems that use an autonomous mobile scanner that will eliminate, or substantially reduce, the requirement that the operator stand in the heat load to operate and move the mobile system.